Theoretically this should work... (but I'm not sure). I have just landed another Tilley X246 "pork pie", but was disappointed that the globe had been cracked in transport. My dear old (long deceased) Dad used to say that you should never give advice that you wouldn't use yourself. So, quite some time ago, I suggested to Matty that he should try this on a globe that had been cracked. Now it's my turn. I used a diamond tipped drill fitted to a Dremel to start the groove; followed by a 1mm steel drill. I etched the end of the crack, then drilled the hole through the glass. The "theory" is, the crack will not travel past the hole: I'll test this out over the next couple of days. Cheers Tony
Time will tell and a good experiment. When you say followed by a 1mm steel drill do you mean a normal twist drill or something special like a tungsten tip drill? Also did you use water when you drilled?
Martin I used a hard stainless steel twist drill. I didn't use water, but I will next time.... Cheers Tony
I'm wondering if a crack can be remelted together? I have a cracked M320 glass in the garage that I will blast with my Mapp gas when I can. Will report if it works.
...Hi there! Re: mending cracked globe... If you are careful with pre heating you may be successful with getting it up to temp with no more fractures, but you will certainly need glass filler rod to fill the crack, otherwise the molten glass will just 'flop'?... Introducing non heat proof glass into the mix may also cause other factors!.... But by far the biggest issue would be the cooling of the glass after reaching a molten state... ...All glass once 'Blown' has to be placed in an Annealing Oven otherwise stress fractures occur... May well be worth a quick gen up on making a small one before the attempt?... ..Remember Mr. Tilley started out as a Glassblower with his famous 'Blowpipe Patent' ?.... ....You might be better off with a Jeweller's type blowtorch......fairly easy to make?.......Meths fuelled?... Gotta be worth a fettle though!..
I'm intrigued Tony, Not being aware of Stainless Steel drills, what applications are they intended for Cheers
I wouldn't dare to try glass welding. You would need to have the whole globe up to just short of melting temp. I think it would be all in bits long before that.
.... They have to keep glass moving when working it, don't they?....Spinning it to keep the shape and putting it back in the furnace to stop it getting cold???... .....Hmmm, perhaps I just might have have been a 'tad' optimistic......ahem.... ....
Stop drilling certainly works well with Aluminium and various other metals, the trick is to be sure you are at the very end of the crack. Sometimes it can be hard to detect with the naked eye. I would never have considered trying it on glass. Nice work Tony.
We all have days like that Tony. I remember telling someone a Pozidrive bit was a Pozitronic bit when they asked what kind it was. I don't even like Star-Trek.
Hey guys, well heating and trying to melt a crack together doesn't work at all!!! I tried it on a cracked glass I had and it did look as if it was forming back together as I applied heat. When it started to cool the crack reappeared and went even further!
Well, I'm no expert but there's glass and then there's glass. Ordinary soda glass is relatively soft and melts at a lowish temperature. That might have been more amenable to treatment, although I doubt it. The heat resistant glass in lamps is borosilicate glass which is harder therefore more brittle and with a higher melting point so unlikely to stand much in the way of interference. I think that also explains why spontaneous breakages occur from time to time...
Tricky stuff glass. Heat causes expansion so a crack appears to close. On removing the heat all that expansion dissipates but causes new stresses not there before. That is what expands the crack. Broken glass is only good for melting down and starting again, so say the Venetians and they should know. (Nearly wrote Venusians there - !?)
There are companies that will repair labware, most of which is borosilicate glass and expensive, but since our globes are the same borosilicate glass they may be able to fix some of them. I don't know about any in the UK, but certainly in the US and Eastern Europe, and I think there is (was) one in Ukraine too. It is a relatively expensive process, so probably best saved for unobtanium globes. Has anyone noticed how Pyrex kitchenware has become more fragile, I have things made of pyrex that are older than me that are pristine, yet, the jug I bought last year is heading for retirement.
Brave sending anything to the Ukraine! Modern Pyrex is sh*te compared to the older stuff. Mind you, so is most anything modern...
Allegedly modern domestic Pyrex has been reformulated to prevent it's use in the production of methamphetamine. I don't know if it's true or not, but modern Pyrex is indeed shite.
The key to doing a repair on pyrex glass is to first anneal the glass to relax any stresses that have built up in it over the years. This can be done in a pottery kiln by gradually heating up the glass to a very high temperature and letting it cool slowly over a day or two. After that, the crack can be sealed / healed by careful application of an oxy-acetylene torch. I watched a lab glass blower repair a very old Coleman 355 globe in this way. The repair was not invisible, but it is strong.
I take it the cost was quite reasonable then? As I know the labware companies are not particularly cheap.
About ten quid at the time. I was not in a hurry and he put it in the oven with the next batch of glassware. The repair itself only took a few minutes of work, evenly pre-heating on a rotating machine almost like a lathe and then heating and sealing the crack. The most interesting part was looking at the stresses in the glass. They have a box with a light shining though a polaroid filter, and a viewing pane also with a filter. If you rotate the glass you can clearly see darker shaded areas and moire patterns inside the glass, which indicates the stressed areas. After the annealing there are were no signs of stress.
